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painted masks



Painted Masks

©2011 Tony Kuyper

Luminosity painting is one of my favorite Photoshop techniques and is described in  this tutorial . It is a method for burning (darkening) and dodging (lightening) specific areas of an image and specific tones in those areas by painting through luminosity selections. The canvas for luminosity painting is a special Burn/Dodge layer set to Soft Light blending mode and filled with 50% gray. Black paint darkens and white paint lightens areas below where it is applied to this canvas, and the luminosity selections direct the paint to pixels of specific tones. The self-feathering nature of the luminosity selections blends the painting seamlessly into the rest of the image.

While luminosity painting can be very useful for burning and dodging an image to balance uneven dark and light tones, the concept of painting through a luminosity selection has other applications that are equally practical. Painting a layer mask for an adjustment layer is a good example. It provides a method to first make a global adjustment using an adjustment layer and then very precisely restricting the adjustment to specific areas and specific tones in the image.

Figure 1 shows the final version of an image where an adjustment layer with a painted luminosity mask played an important role in developing it. The mouse rollover is the image with this adjustment layer's visibility turned off.

Figure 1
Figure 1

Essentially what is happening is that an adjustment layer is affecting the image (darkening it), but only in specific tones and in specific areas. All similar tones are not equally affected, as would be expected with a specific luminosity mask serving as a layer mask for the adjustment. In fact, no single luminosity mask is able to mask the adjustment with the accuracy needed for this particular image. A painted mask, however, is able to do this with relative ease. It augments a luminosity selection to over-reveal the adjustment in some parts of the image, completely conceal the adjustment in others, and even incorporates parts of two different luminosity selections into the same painted mask. In this way, painted masks make luminosity selections even more versatile, allowing greater customization depending on what the image needs.

Because luminosity masks are often used to adjust the tonal values in an image, a good way to approach mask painting with luminosity selections is to start with a global adjustment that either makes the image lighter or darker, or changes its contrast. This could be accomplished in a variety of ways, such as using a Curves or Levels adjustment layer, but another useful option is to simply change the blending mode of the layer to either Screen or Multiply. Multiply blending mode will be used for the example in this tutorial, but a variety of different adjustment layers or blending mode changes could potentially be used to make the initial adjustment.

Multiply blending mode is like placing two identical transparencies in register on a light box. Even though each may be properly exposed, stacking one on top of the other makes the image look much darker, as if it were noticeably underexposed. In a similar way, Multiply blending mode darkens an image except that pure white (255,255,255) and pure black (0,0,0) are unchanged. Figure 2 shows the example image with a Curves adjustment layer set to Multiply blending mode. Notice how the dark areas of the image get really dark, but how the white areas retain their highlight quality.


Figure 2
Figure 2

Screen blending mode does the opposite. It lightens the image and makes it look overexposed. Continuing with the transparency analogy, it's like projecting two identical transparencies onto the same screen in register from different projectors. Even though the individual transparencies may be properly exposed, the dual light sources make the projected image look overexposed. Again, pure black and pure white do not change. Figure 3 shows the example image with a Curves adjustment layer set to Screen blending mode. All but the very darkest areas of the image appear to get brighter.

Figure 3
Figure 3

While clearly excessive when not moderated by a mask or decreased layer opacity, Screen and Multiply blending modes tend to make very natural looking tonal changes to the image when properly applied. Provided that they are used in moderation, these blending modes can subtly and appropriately change image tones without unexpected saturation or contrast changes that sometimes accompany Curves and Levels adjustments.

The blending mode is located in the upper left of the Layers panel (Figure 4). Clicking the box opens the drop-down menu of various blending modes. Blending modes make it possible to have an adjustment layer change the image, sometimes quite substantially, without making any changes in the Adjustment panel dialog box, e.g. no curve bending needed for a Curves adjustment layer. So to either lighten or darken an image in preparation for luminosity painting the layer mask, it's only necessary to create an adjustment layer—Curves or Levels work well—and then change the layer's blending mode to Screen to lighten the image or Multiply to darken it. No change in the Adjustment panel is needed.

Figure 4
Figure 4

So the first thing to do is to create a new adjustment layer. One way to do this is to click the Yin-Yang symbol at the bottom of the Layers panel (green circle, Figure 4) and select either Curves or Layers from the pop-up menu. By default, this method creates a white, reveal-all layer mask on the adjustment layer. Then change the blending mode to either Screen or Multiply, depending on what's desired for the image. Multiply blending mode was used for this image.

Remembering that white reveals and black conceals for layer masks, once the blending mode is changed, the full force of the change will be apparent in the image because the pure white mask conceals nothing. While the chosen blending mode might benefit parts of the image eventually, this full-on change is not desired. To return the image to its original state before this adjustment layer was added, simply type Ctrl+I (Mac: Cmd+I) to invert the layer mask from white to black. This completely hides the adjustment from the image (Figure 5). The menu command Image>Adjustments>Invert can also be used to do this.

Figure 5
Figure 5

NOTE: Another way to create the desired adjustment layer is to use the menu command Layer>New Adjustment Layer>Curves (or Levels). With this method, the blending mode can actually be chosen from the dialog box that pops up. The layer mask will still need to be inverted from white to black after the layer is created.

Once the desired (but exaggerated) adjustment is created and concealed, it's necessary to create a luminosity selection to paint through to reveal the concealed adjustment just where it's needed in the image. The easiest way to get the right selection to paint through is to make an entire series of masks on the Channels panel and choose what works best. For this image, I want to darken some of the lighter tones in the image. Creating selections that target lighter tones would allow the Multiply blending mode to eventually be revealed in only these desired tones. The Lights-series of luminosity masks provides several choices of masks that target progressively lighter tones. The "–All Lights masks" action in the TK-LumMasks(Channels) action set creates these masks in quick order and places them on the Channels Panel (Figure 6).

Figure 6
Figure 6

Masks are graphical representations of selections, with light colors showing selected pixels and black representing pixels that aren't selected. Shades of gray correspond to the degree to which pixels are selected—dark gray pixels are less selected than light gray pixels. Any mask can be turned into a selection with a Ctrl+click (Mac: Cmd+click) on the mask's thumbnail image.

Because these are luminosity masks, the image itself can be seen in the masks. Examine the masks by clicking on them one-by-one on the Channels panel. The mask that shows white (or light gray) in the areas that need to be changed (darkened in this case) would be a good starting point. However, it's also good to think about combining masks to make an even more refined selection to paint through. Generally, for most selections I use for luminosity painting, whether it's on the Burn/Dodge layer or on a layer mask, I'll subtract off the selection at the extreme end of the series. So, for example, in this case I chose the Light Lights mask as targeting the tones I wanted to reveal on the adjustment layer. Instead of just creating a selection from the Light Lights mask and painting through it, I also subtracted off the Super Lights. I want the very lightest tones to stay nearly white, and by subtracting them from the selection that is painted through, they won't receive much paint and will remain essentially concealed from the adjustment and unchanged in the image.

So, after the action creates the Lights-series of masks on the Channels panel, here's the process for creating my desired selection:

  1. Ctrl+click (Mac: Cmd+click) on the Light Lights mask thumbnail—this loads this mask as a selection.
  2. Alt+Ctrl+click (Mac: Opt+Cmd+click) on the Super Lights mask thumbnail—this subtracts these tones from the selection.

I now have a selection that is targeting the tones enclosed by marching ants in Figure 7—light tones are selected but very whitest tones are not.

Figure 7
Figure 7

Subtracted masks of this type often seem to work better for luminosity painting than the straight masks generated by the actions. There are obviously different combinations that might be useful. Lights minus Bright Lights is another subtraction that often works. It targets the darker three-quarter tones. It's also possible to subtract some of the Darks-series masks from the Lights-series of masks to remove mid-tones from the selection. Having entire series of masks (Lights, Darks, or both) on the Channels panel makes creating subtracted masks relatively easy to do.

The next step is to paint through the selection onto the black layer mask to reveal the blending-mode adjustment in the desired parts of the image. There are likely marching ants from loading the selection, and it's helpful to turn them off by typing Ctrl+H (Mac: Cmd+H) so they don't hamper judging the effect that painting has on the image. Once the selection outline is hidden, the selection will still be active and directing paint to the desired tones in the image even though the ants aren't visible.

Before starting to paint, single-click on the black layer mask on the adjustment layer making sure the framing brackets are around the mask. This also makes the layer active and insures that when paint is applied, it goes on the mask on the adjustment layer, where it is intended. If another layer or channel is active, the paint will go there instead, and the desired effect from painting won't be achieved.

The "color" to paint with is easy: white. The mask is 100% black, completely concealing the blending mode adjustment. To reveal the adjustment in the image, white paint needs to be applied to the mask. So make sure the foreground color is white (red square, Figure 8). Type "D" to reset the colors if white is not the foreground color. Typing "X" flips the colors.

Figure 8
Figure 8

Painting is done with a brush, so select the Brush tool by clicking on it on the Tools panel (yellow square, Figure 8) or by typing the letter "B". On the options bar at the top, adjust the hardness to 0% (yellow highlight, Figure 9) using the drop-down menu beside the pixel size.

Figure 9
Figure 9

Brush size is best adjusted by placing the brush over the image and then using the "]" key (right bracket) to increase its size and the "[" key (left bracket) to decrease it. Adjust brush size to be proportional to the area that will be painted.

The opacity setting for painting (green highlight, Figure 9) will depend somewhat on the mask(s) chosen or combined to make the selection being painted through. Selections made from masks with pure or nearly pure white areas in the mask pass more paint through the selection and require a lower opacity setting to reveal the adjustment. A good starting value for opacity in this case is 10 to 20 percent. Selections made by subtraction within the same series will often have the "white" pixels subtracted out of the selection, so a higher opacity setting is necessary to force paint through the "grayer" pixels that remain. Starting with brush opacity at 50% is reasonable for these selections. There will always be some experimentation in mask painting, and opacity is easily reset based on what happens as paint is applied.

Now that this is all set up, it's just a matter of clicking and dragging the mouse across the image in the areas where the adjustment (darkening in this case) needs be revealed. Releasing the mouse stops the painting. Because the adjustment layer and the mask are active, the white paint automatically deposits on the layer mask even though the image itself is visible in Photoshop's main viewing window for evaluation.

One brush stroke is usually NOT sufficient to create the desired or perfect reveal of the blending-mode adjustment. There are two alternatives. If the reveal is insufficient, additional brushstrokes can be applied. Perhaps increasing the opacity or changing the size of the brush will be necessary. However, layering in multiple brushstrokes to slowly reveal the adjustment is often desirable as long as each stroke makes a slightly visible difference. Multiple brushstrokes put additional white paint on the desired pixels on the mask, revealing the adjustment more each time.

If the reveal is too pronounced after a single brushstroke, undo it using Ctrl+Z, (Mac: Cmd+Z), and then lower brush opacity, reduce brush size, or possibly load or create a new, more restrictive selection to paint through.

The goal is to sequentially add white paint to the layer mask to allow some degree of the full-on blending-mode adjustment on the adjustment layer to be revealed in the image to just the desired level in the just the areas where it's desired and in just the tones that need it. By only passing paint through selected or partially-selected pixels, the luminosity selection automatically directs the paint to just the tones that need to be adjusted. While it's necessary to use the mouse to brush those parts of the image where the adjustment is wanted, the active luminosity selection insures that less than perfect mousing keeps paint inside the desired tonal lines.

Looking at the painted mask (Figure 10) can help to better understand what's happening with this type of luminosity painting.

Figure 10
Figure 10

The first thing that can be seen in the mask are outlines of the image itself. Since the primary luminosity mask (Lights) is a gray-scale of the original image, all subsequent luminosity masks derived from this primary mask show image detail as well. A selection created by subtracting different luminosity masks, as was done in this case, still has partially-selected pixels that mimic the luminosity in the original image. Painting through a selection based on the pixel variables in the original image (a pixel-based selection) recreates the contours of the image in all subsequent masks and when painting through these masks. It also helps insure that the painted areas blend perfectly with the rest of the image.

Luminosity painting works because not all pixels receive the same amount of paint. The desired tones that need to be adjusted by the adjustment layer's blending mode receive more paint, and the tones that don't need adjustment receive less or none at all. To increase the effect in certain parts of the image, apply more paint with additional brushstrokes or use a brush with a higher opacity setting. This variability in the final mask is one of the advantages of luminosity painting. Instead of being limited to the selection from a single mask, the mask can be enhanced in any area by simply applying more white paint through the selection. The enhancement can continue until the area being painted is 100% white, a complete reveal of the adjustment layer's adjustment. It's up to the painter—the photographer controlling the mouse—to determine which areas receive paint, a lot, a little, or none at all. The painted mask clearly shows that differing amounts of paint were applied to different areas. Some areas are very white to reveal more of the blending-mode adjustment, some are completely black where no painting occurred at all, and some areas show various levels of gray indicating partial reveal of the layer's adjustment.

This painted mask is actually the result of painting through two different luminosity selections, and it points out another advantage of this technique: It's possible to paint through any number of selections to create the desired reveal of the layer's adjustment, so it's like using several luminosity masks on one layer mask and choosing which parts of them and to what degree they will benefit the image. In this case, most of the painting was done through the Light Lights minus Super Lights selection described above, but when repeated brushstrokes started to reveal darkening in some adjacent areas where darkening was not desired, a Bright Lights minus Super Lights selection was created that excluded even more mid-tones. This new mask better restricted reveal of the adjustment to even lighter tones in the image. This can easily be seen in the mask with some areas adjacent to the whitest tones in the mask still remaining completely black and appropriately showing no change in the image rollover.

This mask-painting technique can take many forms. Once the concept of painting through a pixel-based selection, like a luminosity selection, to create another enhanced pixel-based mask is understood, it's possible to come up with many variations. One of the easiest is to create an adjustment layer with a mask in place and then load that mask as the selection to paint through to enhance it. In other words, the mask becomes the selection for painting to enhance the original mask.

As an example, this same image had a saturation adjustment through a saturation mask to reduce saturation. The saturation mask and Hue/Saturatioin adjustment layer were created together via an action, and the masked adjustment was mostly effective in producing the desired effect. However, in some parts of the image the adjustment wasn't lowering saturation enough before affecting colors whose saturation didn't need to change. So the mask wasn't perfect. It did reveal the right colors to be desaturated, but it didn't quite conceal the colors that needed to be left alone. Painting the mask through a selection of itself quickly solved this problem. A Ctrl+click (Mac: Cmd+click) on the mask's thumbnail image loads it as a selection. White painted is then applied through the selection to the mask in areas that need more reveal of the saturation-lowering adjustment. Black paint can also be applied through the inverse of this selection (Windows: Shift+Ctrl+I/Mac: Shift+Cmd+I) to increase concealment in those areas and colors where saturation should not be changed by the adjustment layer.

Figure 11 shows the original saturation mask and the rollover shows how it looked after being luminosity painted through a selection of itself. The saturation mask was mostly doing the right thing, it just needed a bit more enhancement by painting through a selection of itself to be better tailored for his image.

Figure 11
Figure 11

Figure 12 once again shows the final image. The rollover has the adjustment layer with the painted mask that reduces saturation turned off. Some very subtle increases in saturation are visible in the Figure 12 rollover that correspond to the whitest areas in the rollover of Figure 11. For an online version of the image, this adjustment to lower saturation is probably not needed as it's difficult to appreciate and even see on the monitor. But for the actual print, it's absolutely necessary. Without the adjustment, the areas of oversaturated rock color in the print have a bit of an unbalanced look suggestive of inattentive processing workflow. Properly balancing the saturation, even though it's a small thing, creates a more believable image and removes this sense that something doesn't quite look right when viewing the print. It's these minor adjustments that can help create a personal look for our images and sometimes define the quality of our work. So it's important, I think, to make our prints as good as possible. With a little care, the right tools, and enough desire, it's usually possible to get things looking right.

Figure 12
Figure 12

Once you have a feel for luminosity painting, using it to create or enhance layer masks becomes a logical next step. Painting through a pixel-based selection, like a luminosity or saturation mask, applies paint in proportion to the pixel-based selection(s) in the original mask. The pixel-based quality of the mask is retained so that what is revealed or concealed by the painting blends perfectly into the rest of the image. Very precise masks are possible using this procedure. Selections from multiple pixel-based masks can be used, and they can be painted to any level between pure black and pure white to make the perfect reveal of the underlying adjustment. The effects can be subtle or significant; it all depends on where the light wants to go. I hope that you'll try it and that your images will benefit from this technique.

A PDF version of this tutorial is available in the "Complete Luminosity Masks" and "Complete Catalog" sections on the  Special Offers  page.